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Abstract:

A method for producing a lubricant base oil includes contacting feedstock
containing normal paraffins having not less than 20 carbon atoms with a
first catalyst in the presence of molecular hydrogen to obtain a first
produced oil, and contacting the first produced oil with a second
catalyst in the presence of molecular hydrogen to obtain a second
produced oil. The first catalyst includes a first carrier in which a
fraction of an amount of NH3 to be desorbed at 300 to 800° C.
based on a total amount of NH3 to be desorbed is 80 to 90% in
temperature-programmed desorption of NH3, a first metal selected
from metals of Group VI in the periodic table carried on the first
carrier, and a second metal selected from metals of Group VIII to Group X
in the periodic table carried on the first carrier.

Claims:

1. A method for producing a lubricant base oil, comprising: a first step
of contacting a feedstock containing normal paraffins having not less
than 20 carbon atoms with a first catalyst in the presence of molecular
hydrogen to obtain a first produced oil, and a second step of contacting
the first produced oil with a second catalyst in the presence of
molecular hydrogen to obtain a second produced oil, wherein the first
catalyst comprises a first carrier in which a fraction of an amount of
NH3 to be desorbed at 300 to 800.degree. C. based on a total amount
of NH3 to be desorbed is 80 to 90% in temperature-programmed
desorption of NH3, a first metal that is at least one selected from
metals that belong to Group VI in the periodic table and is carried on
the first carrier, and a second metal that is at least one selected from
metals that belong to Group VIII to Group X in the periodic table and is
carried on the first carrier, a sum C1+C2 of a proportion
C1 (% by mass) of the first metal contained in the first catalyst in
terms of an oxide and a proportion C2 of the second metal contained
in the first catalyst in terms of an oxide (% by mass) is 22 to 36% by
mass, and a ratio D1/D2 between a content of the second metal
D2 (mol) and a content of the first metal D1 (mol) in the first
catalyst is 1.07 to 7.78.

2. The method for producing a lubricant base oil according to claim 1,
wherein in the first produced oil, a proportion of light paraffins having
less than 20 carbon atoms to be contained is 0 to 10% by mass, a
proportion of isomerized paraffins having not less than 20 carbon atoms
to be contained is not less than 70% by mass, a proportion of a sulfur
content to be contained is not more than 10 mass ppm, and a proportion of
a nitrogen content to be contained is not more than 3 mass ppm.

3. The method for producing a lubricant base oil according to claim 1,
wherein the first catalyst contains molybdenum and/or tungsten as the
first metal.

4. The method for producing a lubricant base oil according to claim 1,
wherein the first catalyst contains cobalt and/or nickel as the second
metal.

5. The method for producing a lubricant base oil according to claim 1,
wherein the first catalyst further contains phosphorus carried on the
first carrier, and a proportion of the phosphorus contained in the first
catalyst in terms of an oxide is 0.1 to 8% by mass.

6. The method for producing a lubricant base oil according to claim 1,
wherein in the first catalyst, an average pore radius is 40 to 200 Å;
and a total volume of pores whose pore radius is less than 40 Å is
0.1 to 5% of a total pore volume, and a total volume of pores whose pore
radius is more than 200 Å is 0.1 to 5% of the total pore volume.

7. The method for producing a lubricant base oil according to claim 1,
wherein the first carrier is a carrier containing a complex oxide of
alumina, silica, and zirconia.

8. The method for producing a lubricant base oil according to claim 1,
wherein in the first step, part of the normal paraffins having not less
than 20 carbon atoms is isomerized to isoparaffins.

10. The method for producing a lubricant base oil according to claim 1,
wherein in the first step, a conversion rate of the normal paraffins
represented by a following formula (3) is not less than 70%: conversion
rate of the normal paraffins (%)=[1-(total mass of the normal paraffins
having not less than 20 carbon atoms in the first produced oil)/(the
total mass of the normal paraffins having not less than 20 carbon atoms
in the feedstock)]'100 (3).

11. The method for producing a lubricant base oil according to claim 1,
wherein in the second produced oil, a proportion of the normal paraffins
having not less than 20 carbon atoms is not more than 5% by mass.

12. The method for producing a lubricant base oil according to claim 1,
wherein the second catalyst is a hydrogenation isomerization catalyst
comprising a second carrier and an active metal carried on the second
carrier, the second carrier contains a one-dimensional 10-membered ring
middle pore size zeolite, and at least one porous inorganic oxide
selected from alumina, silica, zirconia, titania, magnesia, and boria,
and the active metal is platinum and/or palladium.

13. The method for producing a lubricant base oil according to claim 1,
wherein in the second step, a conversion rate of the normal paraffins
represented by a following formula (4) is not less than 95%: conversion
rate of the normal paraffins (%)=[1-(total mass of the normal paraffins
having not less than 20 carbon atoms in the second produced oil)/(total
mass of the normal paraffins having not less than 20 carbon atoms in the
first produced oil)]×100 (4).

14. The method for producing a lubricant base oil according to claim 1,
wherein the second produced oil is further subjected to hydrorefining.

15. The method for producing a lubricant base oil according to claim 1,
wherein the first step and the second step are performed to obtain at
least one lubricant base oil selected from the group consisting of: a 70
Pale lubricant base oil in which a boiling point is 340 to 410.degree.
C., a viscosity index is not less than 105, a pour point is not more than
-25.degree. C., a sulfur content is not more than 5 mass ppm, an SAE 10
lubricant base oil in which a boiling point is 390 to 470.degree. C., a
viscosity index is not less than 130, a pour point is not more than
-12.5.degree. C., and a sulfur content is not more than 5 mass ppm, an
SAE 20 lubricant base oil in which a boiling point is 450 to 520.degree.
C., a viscosity index is not less than 130, a pour point is not more than
-12.5.degree. C., and a sulfur content is not more than 5 mass ppm, and
an SAE 30 lubricant base oil in which a boiling point is 510 to
550.degree. C., a viscosity index is not less than 130, a pour point is
not more than -10.degree. C., and a sulfur content is not more than 5
mass ppm.

Description:

TECHNICAL FIELD

[0001] The present invention relates to a method for producing a lubricant
base oil.

BACKGROUND ART

[0002] Among petroleum products, jet fuels, diesel oils, lubricant oils,
and the like are the products whose fluidity at a low temperature is
important. For this reason, desirably, in a base oil used for these
products, wax components such as normal paraffins that cause the fluidity
at a low temperature to be reduced are completely or partially removed,
or converted to a component other than the wax components. Moreover,
recently, hydrocarbon oils obtained by a Fischer-Tropsch synthesis
(hereinafter, written as the "FT synthesis" in some cases) have received
attention as a feedstock for producing fuel oils and lubricant oils
because the content of substances of concern such as sulfur is small;
however, a large amount of the wax components are contained also in the
hydrocarbon oils.

[0003] As a dewaxing technique for removing a wax component from a
hydrocarbon oil, a method of extracting a wax component by a solvent such
as liquefied propane and methyl ethyl ketone is known. However, in the
method, there are problems such as increase in the scale of the
apparatus, expensive operating cost, limitation of the kind of an
applicable feedstock, and limitation of the yield of the product by the
kind of the feedstock.

[0004] On the other hand, as a dewaxing technique for converting a wax
component in a hydrocarbon oil into a non-wax component, a contact
dewaxing technique is known in which a hydrocarbon oil is contacted with
a hydrogenation isomerization dewaxing catalyst having both a
hydrogenation-dehydrogenation ability and an isomerization ability in the
presence of molecular hydrogen to isomerize normal paraffins in the
hydrocarbon oil to isoparaffins, for example.

[0005] The contact dewaxing is effective as a method for improving the
fluidity at a low temperature of the hydrocarbon oil, but a conversion
rate of the normal paraffins needs to be sufficiently high in order to
obtain a fraction suitable for a base oil for a lubricant oil. However, a
hydrogenation isomerization catalyst used in the contact dewaxing has
both an isomerization ability and an ability to crack hydrocarbons; for
this reason, cracking of the hydrocarbon oil and production of lighter
products progress as the conversion rate of the normal paraffins is
increased, and it is difficult to obtain a desired fraction with high
efficiency. Particularly, in production of a high quality base oil for a
lubricant oil of which a high viscosity index and a low pour point are
demanded, it is very difficult to obtain a target fraction economically;
for this reason, synthetic base oils such as poly-alpha-olefins have been
used often in the field.

[0006] From such a circumstance, in the field of production of the
lubricant base oil, a dewaxing technique for efficiently obtaining a
desired isoparaffin fraction from a hydrocarbon oil containing a wax
component has been demanded.

[0007] So far, an attempt to improve the isomerization selectivity of the
hydrogenation isomerization catalyst used in the contact dewaxing has
been made. For example, Patent Literature 1 below discloses a process in
which a linear or slightly branched hydrocarbon raw material having not
less than 10 carbon atoms is contacted under an isomerization condition
with a catalyst comprising a molecular sieve such as ZSM-22, ZSM-23,
ZSM-48 containing a metal of Group VIII to Group X in the periodic table
and having one-dimensional pores of a middle size in which the size of a
crystallite does not exceed approximately 0.5 μ, thereby to produce a
dewaxed lubricant oil (Patent Literature 1).

CITATION LIST

Patent Literature

[0008] Patent Literature 1: U.S. Pat. No. 5,282,958

SUMMARY OF INVENTION

Technical Problem

[0009] However, even in the process for producing a lubricant base oil
described in Patent Literature 1, it cannot be said that the
isomerization selectivity of the catalyst is sufficient, and it is
difficult to obtain an isoparaffin fraction suitable for a desired
lubricant base oil from a hydrocarbon oil containing a normal paraffin
component with a high yield. Particularly, in production of a high
quality lubricant base oil, the conversion rate of the lubricant base oil
needs to be increased to the extent that normal paraffins are
substantially not contained; in this case, a cracking reaction of normal
paraffins and/or isoparaffins that are isomerized product is active, and
it is difficult to obtain a target lubricant base oil with an economical
yield.

[0010] The present invention has been made in consideration of the
problems above, and an object of the present invention is to provide a
method for producing a lubricant base oil in which a high quality
lubricant base oil can be stably obtained from a feedstock containing
normal paraffins with a high yield.

Solution to Problem

[0011] Namely, the present invention provides a method for producing a
lubricant base oil, comprising: a first step of contacting a feedstock
containing normal paraffins having not less than 20 carbon atoms with a
first catalyst in the presence of molecular hydrogen to obtain a first
produced oil, and a second step of contacting the first produced oil with
a second catalyst in the presence of molecular hydrogen to obtain a
second produced oil, wherein the first catalyst comprises a first carrier
in which a fraction of an amount of NH3 to be desorbed at 300 to
800° C. based on a total amount of NH3 to be desorbed is 80
to 90% in temperature-programmed desorption of NH3 (NH3-TPD), a
first metal that is at least one selected from metals that belong to
Group VI in the periodic table and is carried on the first carrier, and a
second metal that is at least one selected from metals that belong to
Group VIII to Group X in the periodic table and is carried on the first
carrier; a sum C1+C2 of a proportion C1 of the first metal
contained in the first catalyst in terms of an oxide (% by mass) and a
proportion C2 of the second metal contained in the first catalyst in
terms of an oxide (% by mass) is 22 to 36% by mass; and a ratio
D1/D2 between a content of the second metal D2 (mol) and a
content of the first metal D1 (mol) in the first catalyst is 1.07 to
7.78.

[0012] According to the method for producing a lubricant base oil
according to the present invention, a high quality lubricant base oil can
be stably obtained from a feedstock containing normal paraffins having
not less than 20 carbon atoms with a high yield. More specifically, a
problem of the conventional method for producing a lubricant base oil is
that if the conversion rate of the normal paraffins is sufficiently
increased, the yield is undesirably reduced by a hydrocracking reaction
of the normal paraffins that occurs at the same time. Moreover, if the
hydrocracking reaction is suppressed, the conversion rate of the normal
paraffins is reduced. When the conversion rate of the normal paraffins is
reduced, a need to remove excessive normal paraffins is produced in the
subsequent dewaxing step, resulting in reduction in the yield. Contrary
to this, according to the method for producing a lubricant base oil
according to the present invention, in the feedstock containing normal
paraffins having not less than 20 carbon atoms, while the hydrocracking
reaction can be suppressed, hydrodesulfurization, hydrogenation
denitrification, and hydrogenation isomerization can be efficiently
progressed. In the thus-obtained produced oil, the total content of the
respective paraffins having not less than 20 carbon atoms is
approximately the same as that in the feedstock, the contents of sulfur
and nitrogen are sufficiently reduced, and most of the normal paraffins
having not less than 20 carbon atoms are converted to isomerized
paraffins having not less than 20 carbon atoms.

[0013] In the method for producing a lubricant base oil according to the
present invention, preferably, the first step is performed so that in the
first produced oil, the proportion of light paraffins having less than 20
carbon atoms to be contained is 0 to 10% by mass, the proportion of
isomerized paraffins having not less than 20 carbon atoms to be contained
is not less than 70% by mass, the proportion of sulfur to be contained is
not more than 10 mass ppm, and the proportion of nitrogen to be contained
is not more than 3 mass ppm. According to such a production method, the
effect above is more remarkably obtained.

[0014] Preferably, the first catalyst contains molybdenum and/or tungsten
as the first metal, and cobalt and/or nickel as the second metal.
According to such a catalyst, the hydrocracking reaction accompanying
hydrogenation isomerization can be further suppressed.

[0015] Moreover, preferably, the first catalyst further contains
phosphorus carried on the first carrier, and the proportion of the
phosphorus in the first catalyst in terms of an oxide is 0.1 to 8% by
mass. Such a catalyst is likely to further improve the activity of the
catalyst.

[0016] Moreover, preferably, in the first catalyst, the average pore
radius is 40 to 200 Å, the total volume of pores whose pore radius is
less than 40 Å is 0.1 to 5% of the total pore volume, and the total
volume of pores whose pore radius is more than 200 Å is 0.1 to 5% of
the total pore volume. According to such a catalyst,
hydrodesulfurization, hydrogenation denitrification, and hydrogenation
isomerization can be progressed more efficiently.

[0017] Preferably, the first carrier is a carrier containing a complex
oxide of alumina, silica, and zirconia. If the first catalyst contains
such a carrier, the first catalyst can further suppress the hydrocracking
reaction accompanying hydrogenation isomerization, and securely has
mechanical strength durable in commercial use.

[0018] In the first step, part or all of the normal paraffins having not
less than 20 carbon atoms is isomerized to isoparaffins.

[0020] In the method for producing a lubricant base oil according to the
present invention, preferably, the first step is performed so that the
conversion rate of the normal paraffins represented by the following
formula (3) is not less than 70%. According to the first produced oil
obtained at such a conversion rate, a high quality lubricant base oil can
be obtained with a higher yield.

Conversion rate of the normal paraffins (%)=[1-(total mass of the normal
paraffins having not less than 20 carbon atoms in the first produced
oil)/(total mass of the normal paraffins having not less than 20 carbon
atoms in the feedstock)]×100 (3)

[0021] In the method for producing a lubricant base oil according to the
present invention, preferably, the second step is performed so that the
proportion of the normal paraffins having not less than 20 carbon atoms
to be contained in the second produced oil is not more than 5% by mass.
According to such a production method, a high quality lubricant base oil
can be obtained with a higher yield.

[0022] Preferably, the second catalyst is a hydrogenation isomerization
catalyst comprising a second carrier and an active metal carried on the
second carrier, wherein the second carrier contains a one-dimensional
10-membered ring middle pore size zeolite and at least one porous
inorganic oxide selected from alumina, silica, zirconia, titania,
magnesia, and boria, and the active metal is platinum and/or palladium.
According to such a catalyst, because hydrogenation isomerization
progresses more efficiently, a high quality lubricant base oil can be
obtained with a higher yield.

[0023] In the method for producing a lubricant base oil according to the
present invention, preferably, the second step is performed so that the
conversion rate of the normal paraffins represented by the following
formula (4) is not less than 95%. According to such a production method,
a high quality lubricant base oil can be obtained with a higher yield.

Conversion rate of the normal paraffins (%)=[1-(total mass of the normal
paraffins having not less than 20 carbon atoms in the second produced
oil)/(total mass of the normal paraffins having not less than 20 carbon
atoms in the first produced oil)]×100 (4)

[0024] In the method for producing a lubricant base oil according to the
present invention, the second produced oil may be further subjected to
hydrorefining. The second produced oil is subjected to hydrogenation
isomerization while the hydrocracking reaction is suppressed. For this
reason, the condition in the hydrorefining may be milder than that in the
hydrorefining conventionally performed, and reduction in the yield caused
by the hydrocracking reaction accompanying the hydrogenation treatment
can be reduced.

[0025] In the method for producing a lubricant base oil according to the
present invention, preferably, the first step and the second step are
performed to obtain at least one lubricant base oil selected from the
group consisting of a 70 Pale lubricant base oil whose boiling point is
340 to 410° C., viscosity index is not less than 105, pour point
is not more than -25° C., and sulfur content is not more than 5
mass ppm; an SAE 10 lubricant base oil in which a boiling point is 390 to
470° C., a viscosity index is not less than 130, a pour point is
not more than -12.5° C., and a sulfur content is not more than 5
mass ppm; an SAE 20 lubricant base oil in which a boiling point is 450 to
520° C., a viscosity index is not less than 130, a pour point is
not more than -12.5° C., and a sulfur content is not more than 5
mass ppm; and an SAE 30 lubricant base in which a boiling point is 510 to
550° C., a viscosity index is not less than 130, a pour point is
not more than -10° C., and a sulfur content is not more than 5
mass ppm. These lubricant base oils have sufficiently practical
performance, and according to the production method of the present
invention, even such a high quality lubricant base oil can be obtained
with a high yield.

Advantageous Effects of Invention

[0026] According to the present invention, a method for producing a
lubricant base oil in which a high quality lubricant base oil can be
stably obtained from a feedstock containing normal paraffins with a high
yield can be provided.

DESCRIPTION OF EMBODIMENTS

[0027] Hereinafter, a suitable embodiment according to the present
invention will be described in detail.

[0028] (First step)

[0029] In a first step in the method for producing a lubricant base oil
according to the present embodiment, a feedstock containing normal
paraffins having not less than 20 carbon atoms is contacted with a first
catalyst in the presence of molecular hydrogen to obtain a first produced
oil. The first catalyst comprises a first carrier in which the fraction
of the amount of NH3 to be desorbed at 300 to 800° C. based
on the total amount of NH3 to be desorbed is 80 to 90% in
temperature-programmed desorption of NH3 (NH3-TPD), a first
metal that is at least one selected from metals that belong to Group VI
in the periodic table and is carried on the first carrier, and a second
metal that is at least one selected from metals that belong to Group VIII
to Group X in the periodic table and is carried on the first carrier.
Moreover, the sum C1+C2 of a proportion C1 of the first
metal contained in the first catalyst in terms of an oxide (% by mass)
and a proportion C2 of the second metal contained in the first
catalyst in terms of an oxide (% by mass) is 22 to 36% by mass, and the
ratio D1/D2 between a content of the second metal D2 (mol)
and a content of the first metal D1 (mol) in the first catalyst is
1.07 to 7.78.

[0030] In the first step, the sulfur content and nitrogen content in the
feedstock are removed, and part of the normal paraffins having not less
than 20 carbon atoms is isomerized to isoparaffins. In the first step,
while hydrocracking of the normal paraffins is suppressed,
hydrodesulfurization, hydrogenation denitrification, and hydrogenation
isomerization can be progressed efficiently. Namely, according to the
first step, a produced oil can be obtained in which the total content of
the respective paraffins having not less than 20 carbon atoms is
approximately the same as that in the feedstock, the contents of sulfur
and nitrogen are sufficiently reduced, and most of the normal paraffins
having not less than 20 carbon atoms is converted to the isomerized
paraffins having not less than 20 carbon atoms; and a high quality
lubricant base oil can be obtained from such a produced oil with a high
yield. The term "high quality" means that environmental load is small
because the content of sulfur is small, and high fuel efficiency can be
achieved because of high performance at a low temperature.

[0031] The method for producing a lubricant base oil according to the
present embodiment may further comprise steps such as hydrorefining and
fractionation when necessary after the first step and a second step in
which hydrogenation dewaxing is performed. In these steps, in the first
produced oil, isomerization of the normal paraffins is sufficiently
performed while the hydrocracking reaction is suppressed; for this
reason, a sufficiently high quality lubricant base oil can be obtained on
a condition milder than that in the conventional hydrogenation dewaxing,
hydrorefining, fractionation, and the like. For this reason, a high
quality lubricant base oil can be obtained with a high yield.

[0032] As the feedstock, at least one selected from the group consisting
of slack waxes, dewaxed oils, paraffin waxes, microcrystalline waxes,
petrolatum, Fischer-Tropsch waxes, light vacuum gas oils, hydrocracked
vacuum gas oils, hydrocracked atmospheric residue, and hydrocracked
vacuum residue can be suitably used. These feedstocks are available
economically and stably.

[0033] The first catalyst used in the first step comprises a first
carrier, a first metal that is at least one selected from metals that
belong to Group VI in the periodic table and is carried on the first
carrier, and a second metal that is at least one selected from metals
that belong to Group VIII to Group X in the periodic table and is carried
on the first carrier as active metals. The first catalyst may further
comprise a metal other than the first metal and the second metal.
Preferably, the first metal and the second metal are carried on the first
carrier as an oxide.

[0034] As the first carrier, those preferably have solid acidity;
preferable are those in which the fraction of the amount of NH3 to
be desorbed at 300 to 800° C. based on the total amount of
NH3 to be desorbed is 80 to 90% in temperature-programmed desorption
of NH3 (NH3-TPD); and more preferable are those in which the
fraction of the amount of NH3 to be desorbed at 300 to 800°
C. based on the total amount of NH3 to be desorbed is 81% to 89.5%
from the viewpoint of further improving the yield of the lubricant base
oil.

[0035] Here, the "temperature-programmed desorption of NH3" refers to
a method described in following literatures (Sawa M., Niwa M., Murakami
Y., Zeolites 1990, 10, 532, Karge H. G., Dondur V., J. Phys. Chem. 1990,
94, 765, and others), and is performed as follows. First, a carrier is
pre-treated under a nitrogen stream at a temperature of not less than
400° C. for not less than 30 minutes to remove adsorbed molecules,
and NH3 is introduced into the catalyst to adsorb at 100° C.
until NH3 is saturated. Next, the temperature of the carrier is
increased from 100 to 800° C. at a temperature ramping rate of not
more than 10° C./min to desorb NH3, and NH3 separated by
desorption is monitored at each predetermined temperature. Then, the
fraction of the amount of NH3 to be desorbed at 300° C. to
800° C. to the total amount of NH3 to be desorbed (the amount
of desorption at 100 to 800° C.) is determined.

[0036] Preferably, the first carrier is an amorphous carrier containing a
complex oxide of alumina, silica, and zirconia. The catalyst containing
such a carrier can further suppress the hydrocracking reaction
accompanying hydrogenation isomerization, and has mechanical strength
durable in commercial use.

[0037] In the first catalyst, C1+C2 is 22 to 36% by mass wherein
the proportion of the contained first metal in terms of an oxide to the
total amount of the first catalyst is C1 (% by mass), and the
proportion of the contained second metal in terms of an oxide to the
total amount of the first catalyst is C2 (% by mass); from the
viewpoint of being capable of further suppressing the hydrocracking
reaction, C1+C2 is preferably 24 to 33% by mass, and more
preferably 25 to 30% by mass.

[0038] C1 (% by mass) is a value determined by the following formula
(1), and C2 (% by mass) is a value determined by the following
formula (2).

[ Expression 1 ] C 1 = Mass of
the first metal contained in the
first catalyst in terms of
an oxide Total mass of the
first catalyst × 100 ( 1 ) C 2 = Mass
of the second metal contained in
the first catalyst in terms
of an oxide Total mass of
the first catalyst × 100 ( 2 ) ##EQU00001##

[0039] Here, the "mass of the first metal contained in the first catalyst
in terms of an oxide" indicates the mass of an oxide of the first metal
with the same molar amount as the content of the first metal in the first
catalyst (mol). Namely, if the content of the first metal is X mol, the
"mass of the first metal contained in the first catalyst in terms of an
oxide" indicates the mass equivalent to the mass of X mol of the oxide of
the first metal. Moreover, the "mass of the second metal contained in the
first catalyst in terms of an oxide" indicates the mass of an oxide of
the second metal with the same molar amount as the content of the second
metal in the first catalyst (mol).

[0040] Moreover, in the first catalyst, the ratio D1/D2 between
a content of the second metal D2 (mol) and the content of the second
metal D1 (mol) is 1.07 to 7.78; from the viewpoint of being capable
of further suppressing the hydrocracking reaction, the ratio is
preferably not less than 2.08 and more preferably not less than 2.25;
moreover, the ratio is preferably not more than 6.75 and more preferably
not more than 5.71.

[0041] Preferably, the first catalyst contains molybdenum and/or tungsten
as the first metal, and cobalt and/or nickel as the second metal.
According to such a catalyst, the hydrocracking reaction accompanying
hydrogenation isomerization can be further suppressed.

[0042] In the first catalyst, the average pore radius of the catalyst
determined by a BET method according to the nitrogen adsorption method is
40 to 200 Å, and more preferably 60 to 150 Å. At an average pore
radius less than 40 Å, diffusion of reaction molecules (for example,
the normal paraffins having not less than 20 carbon atoms, the sulfur
content, the nitrogen content, and the like) within pores is not
sufficiently performed, and the activity of the catalyst may be reduced.
Moreover, at an average pore radius more than 200 Å, because the
surface area of the catalyst is reduced, the activity of the catalyst is
likely to be reduced.

[0043] In the first catalyst, the total volume of pores whose pore radius
is less than 40 Å is preferably 0.1 to 5% of the total pore volume,
and more preferably 0.1 to 3%. While easiness of diffusion of the
reaction molecules in the pore whose pore radius is less than 40 Å is
inferior to that in the pores whose pore radius is larger than that
above, contribution to the desulphurization reaction cannot be neglected;
if the total volume of pores is less than 0.1%, the effective surface
area of the catalyst may be reduced to reduce the activity of the
catalyst. On the other hand, if the total volume of pores is more than
5%, the activity of the catalyst may be conversely reduced by an
influence of diffusion.

[0044] In the first catalyst, the total volume of pores whose pore radius
is more than 200 Å is preferably 0.1 to 5% of the total pore volume,
and more preferably 0.1 to 4%. It is thought that the pores whose pore
radius is more than 200 Å are important pores that influence a degree
at which the reaction molecules reach reaction active sites. If the total
volume of the pores whose pore radius is more than 200 Å is less than
0.1%, diffusion of the reaction molecules is not sufficient, and the
activity of the catalyst may be reduced; it is thought that if the total
volume of the pores is more than 5%, the surface area of the catalyst
itself is reduced to reduce the activity of the catalyst. According to
such a catalyst, hydrodesulfurization, hydrogenation denitrification, and
hydrogenation isomerization can be progressed more efficiently.

[0045] A method for carrying the first metal and the second metal on a
carrier is not particularly limited, and a known method usually used when
a catalyst is produced can be used. As such a method, a method for
impregnating a solution containing salts of the first metal and the
second metal to a carrier is preferably used. Moreover, an Equilibrium
adsorption method, a Pore-filling method, an Incipient-wetness method,
and the like are preferably used. For example, the Pore-filling method is
a method in which the volume of the pore in the carrier is measured in
advance, and the same volume of a metal salt solution is impregnated; the
method for impregnation is not particularly limited, and impregnation can
be performed by a suitable method depending on the amount of the metal to
be carried and physical properties of the carrier.

[0046] Preferably, the first step is performed so that the content of the
light paraffins having less than 20 carbon atoms is 0 to 10% by mass, the
content of the isomerized paraffins having not less than 20 carbon atoms
is not less than 70% by mass, the content of sulfur is not more than 10
mass ppm, and the content of nitrogen is not more than 3 mass ppm in the
first produced oil. According to such a produced oil, the lubricant base
oil can be obtained with a higher yield. Moreover, in the second step
(hydrogenation dewaxing step) described later, if the sulfur content and
nitrogen content in the first produced oil are sufficiently reduced, the
activity of a second catalyst (hydrogenation dewaxing catalyst) is not
impaired, and hydrogenation dewaxing progresses efficiently.

[0047] Moreover, in the first step, the conversion rate of the normal
paraffins represented by the following formula (3) is preferably not less
than 70%.

Conversion rate of the normal paraffins (%)=[1-(total mass of the normal
paraffins having not less than 20 carbon atoms in the first produced
oil)/(total mass of the normal paraffins having not less than 20 carbon
atoms in the feedstock)]×100 (3)

[0048] The contact condition on the feedstock and the first catalyst in
the first step is preferably the hydrogen partial pressure of 3 to 20
MPa, the average reaction temperature in the catalyst layer of 250 to
450° C., the LHSV of 0.5 to 5.0 h-1, and the hydrogen/oil
ratio of 1000 to 8000 scf/b, for example. According to such a condition,
the suitable first produced oil above can be easily obtained. Moreover,
the contact condition is particularly suitable in the case where the
feedstock contains the normal paraffins having not less than 20 carbon
atoms, not less than 500 mass ppm of the sulfur content, and not less
than 10 mass ppm of the nitrogen content.

[0049] In the method for producing a lubricant base oil according to the
present embodiment, steps such as hydrogenation dewaxing, solvent
dewaxing, hydrorefining, and fractionation are further performed when
necessary to obtain a lubricant base oil.

[0050] In the conventional method for producing a lubricant base oil, if
refinement is performed to the extent that the normal paraffins are
substantially not contained, a sufficient yield cannot be obtained due to
loss of the paraffin component along with the refining operation.
Contrary to this, in the production method according to the present
invention, because isomerized paraffins can be efficiently obtained in
the first step, loss of the paraffin component along with the refining
operation is small, and a high quality lubricant base oil can be obtained
with a high yield.

[0051] In the method for producing a lubricant base oil according to the
present embodiment, from the viewpoint of obtaining a higher quality
lubricant base oil, the first produced oil may be further subjected to a
hydrogenation treatment. The first produced oil is subjected to
hydrogenation isomerization while the hydrocracking reaction is
suppressed. For this reason, the condition of the hydrogenation treatment
may be milder than that in the hydrogenation treatment conventionally
performed, and reduction in the yield caused by the hydrocracking
reaction accompanying the hydrogenation treatment can be suppressed.

[0052] The hydrogenation treatment may be single stage or multi-stage.
Examples of the hydrogenation treatment include hydrogenation dewaxing
and hydrorefining; by combining these when necessary, a lubricant base
oil having desired properties can be obtained.

[0053] Hereinafter, as an example of a suitable production method, a
production method will be described in which the first produced oil is
subjected to hydrogenation dewaxing (in the second step (hydrogenation
dewaxing step)), and then subjected to hydrorefining (hydrorefining
step), and the obtained base oil is fractionated to obtain a desired
lubricant base oil (fractionation step).

[0054] (Second Step)

[0055] In the second step, the first produced oil and the second catalyst
are contacted with each other in the presence of molecular hydrogen to
obtain a second produced oil. The second produced oil obtained here is
preferably subjected to hydrogenation dewaxing, namely, substantially
does not contain the normal paraffins having not less than 20 carbon
atoms (namely, the proportion of the normal paraffins having not less
than 20 carbon atoms is not more than 5% by mass). The second step is the
so-called hydrogenation dewaxing step.

[0056] As the second catalyst, a known hydrogenation isomerization
catalyst can be used; for example, a catalyst comprising a carrier
(hereinafter, referred to as a "second carrier.") and an active metal
carried on the second carrier (hereinafter, referred to as a "third
metal.") is preferable, and a bifunctional catalyst in which the second
carrier has solid acidity is more preferable. Examples of the second
carrier include a mixture of a one-dimensional 10-membered ring middle
pore size zeolite and at least one porous inorganic oxide selected from
alumina, silica, zirconia, titania, magnesia, and boria. Among these, as
the one-dimensional 10-membered ring middle pore size zeolite, at least
one zeolite selected from ZSM-22, ZSM-23, and ZSM-48 is preferable.
Moreover, as the third metal carried on the second carrier, platinum
and/or palladium is preferable.

[0057] In the second step, the conversion rate of the normal paraffins
represented by the following formula (4) is preferably not less than 95%.

Conversion rate of the normal paraffins (%)=[1-(total mass of the normal
paraffins having not less than 20 carbon atoms in the second produced
oil)/(total mass of the normal paraffins having not less than 20 carbon
atoms in the first produced oil)]×100 (4)

[0058] In the second step, hydrogenation dewaxing is preferably performed
at a hydrogen partial pressure of 0.5 to 20 MPa, an average reaction
temperature in the catalyst layer of 250 to 400° C., an LHSV of
0.5 to 10.0 h-1, and a hydrogen/oil ratio of 1000 to 10000 scf/b,
for example.

[0059] (Hydrorefining (Hydrofinishing) Step)

[0060] In the hydrorefining step, the second produced oil and a third
catalyst are contacted with each other in the presence of molecular
hydrogen to obtain a third produced oil. In the hydrorefining step,
olefin components and polycyclic aromatic compounds in the second
produced oil can be hydrogenated to improve hue and/or oxidation
stability.

[0061] As the third catalyst, known hydrorefining catalysts can be used;
those preferably contain a carrier and a metal carried on the carrier.
Examples of the carrier include alumina, silica, zirconia, titania, and
boria. Moreover, examples of the metal carried on the carrier include
nickel, molybdenum, cobalt, tungsten, palladium, and platinum. A
plurality of metals may be carried on the carrier, and a combination of
platinum-palladium, that of nickel-molybdenum, that of cobalt-molybdenum,
that of nickel-tungsten, and the like are suitable.

[0062] In the hydrorefining step, hydrorefining is preferably performed at
a hydrogen partial pressure of 1 to 20 MPa, a average reaction
temperature in the catalyst layer of 200 to 350° C., an LHSV of
0.1 to 10.0 h-1, and a hydrogen/oil ratio of 1000 to 10000 scf/b,
for example.

[0063] (Fractionation Step)

[0064] In the fractionation step, a lubricant oil fraction is distilled
and separated from the third produced oil. At this time, a fuel oil
fraction as a light content may be obtained.

[0065] In the fractionation step, the third produced oil can be distilled
under reduced pressure to suitably obtain lubricant base oils referred to
as 70 Pale, SAE 10, SAE 20, and SAE 30. More specifically, in the
fractionation step, as the lubricant base oils corresponding to 70 Pale,
SAE 10, SAE 20, and SAE 30, the lubricant base oils each having
properties below can be obtained. An NOACK evaporation loss indicates the
amount of evaporation loss measured according to ASTM D5800.

[0066] 70 Pale: the boiling point is 340 to 410° C., the kinematic
viscosity at 100° C. is 2.2 to 3.8 mm2/s, the viscosity index
is not less than 105, the pour point is not more than -25° C., and
the sulfur content is not more than 5 mass ppm.

[0067] SAE 10: the boiling point is 390 to 470° C., the kinematic
viscosity at 100° C. is 3.5 to 5.6 mm2/s, the viscosity index
is not less than 130, the CCS viscosity at -30° C. is not more
than 2800, the NOACK evaporation loss is not more than 16% by mass, the
pour point is not more than -12.5° C., and the sulfur content is
not more than 5 mass ppm.

[0068] SAE 20: the boiling point is 450 to 520° C., the kinematic
viscosity at 100° C. is 5.6 to 9.3 mm2/s, the viscosity index
is not less than 130, the pour point is not more than -12.5° C.,
and the sulfur content is not more than 5 mass ppm.

[0069] SAE 30: the boiling point is 510 to 550° C., the kinematic
viscosity at 100° C. is 9.3 to 12.5 mm2/s, the viscosity
index is not less than 130, the pour point is not more than -10°
C., and the sulfur content is not more than 5 mass ppm.

[0070] The lubricant base oil obtained according to the method for
producing a lubricant base oil according to the present embodiment itself
has high thermal stability and oxidation stability; in the case where
additives are further blended with the lubricant base oil, while the
additives are dissolved and kept in the lubricant base oil sufficiently
stably, the functions of the additives can be demonstrated at a higher
level. For this reason, in a lubricant oil composition in which an
antioxidant is blended with the lubricant base oil, thermal stability and
oxidation stability at a high level can be achieved. For example, in the
case where the obtained lubricant base oil corresponds to 70 Pale, the
RBOT life can be not less than 290 min. Moreover, in the case where the
obtained lubricant base oil corresponds to SAE 10, the RBOT life can be
not less than 350 min. Moreover, in the case where the obtained lubricant
base oil corresponds to SAE 20, the RBOT life can be not less than 400
min. The RBOT life in the present invention means a RBOT value measured
according to JIS K 2514 in a composition in which 0.2% by mass of a
phenol antioxidant (2,6-di-tert-butyl-p-cresol; DBPC) is added to the
lubricant base oil.

[0071] Further, according to the lubricant base oil obtained by the
production method according to the present embodiment, because the
viscosity-temperature properties and friction properties of the lubricant
base oil itself are high, improvement in a friction reduction effect and
improvement in energy-saving properties can be achieved. Further, in the
lubricant base oil, the additives are highly effective; for this reason,
in the case where a friction reducing agent is blended with the lubricant
base oil, improvement in the friction reduction effect and improvement in
the energy-saving properties can be achieved.

[0072] The lubricant base oil obtained by the production method according
to the present embodiment has high properties as described above, and can
be suitably used as a base oil for various lubricant oils. Examples of
application of the lubricant base oil specifically include a lubricant
oil used for internal combustion engines (lubricant oil for internal
combustion engines)such as gasoline engines for automobiles, gasoline
engines for two-wheeled vehicles, diesel engines, gas engines, engines
for gas heat pumps, engines for ships, and generator engines, a lubricant
oil used for driving and transmitting apparatuses (oil for driving and
transmitting apparatuses)such as automatic transmissions, manual
transmissions, continuously variable transmissions, and final drives,
hydraulic oils used for hydraulic apparatuses such as buffers and
construction machines, compressor oils, turbine oils, gear oils,
refrigeration oils, and oil agents for processing metals; if the
lubricant base oil according to the present invention is used in these
applications, improvement in properties such as the viscosity-temperature
properties, thermal stability, oxidation stability, energy-saving
properties, fuel efficiency, a longer life of the lubricant oil, and
reduction in the substances of concern in the respective lubricant oils
can be achieved at a high level.

EXAMPLES

Examples 1 to 12, Comparative Examples 1 to 9

[0073] An amorphous alumina silica zirconia complex oxide according to
Example 1 was prepared according to the following method. First, Solution
A, Solution B, and Solution C are prepared. Solution A: a solution in
which 20 g of an aluminum sulfate 16-hydrate reagent is dissolved in 90
ml of ion exchange water. Solution B: a solution in which 11.4 g of
liquid glass No. 3 is dissolved in 50 ml of ion exchange water. Solution
C: a solution in which 2.3 g of a zirconium sulfate tetrahydrate reagent
is dissolved in 50 ml of ion exchange water.

[0074] Next, Solution B was gelated at pH 14, and Solution C was added to
the slurry aged at pH 7 for 2 hours; further, the slurry was adjusted at
pH 7 to produce silica zirconia complex hydroxide. Solution A was added
to silica zirconia complex hydroxide to adjust the slurry at pH 7 to
produce silica zirconia alumina complex hydroxide. The obtained slurry
was filtered, washed, and heated and condensed to adjust moisture; then,
the slurry was extrusion molded, dried, and burned to obtain an extruded
product (carrier) with a diameter of approximately 1.5 mm and a length of
approximately 10 mm. About the obtained carrier, temperature-programmed
desorption of NH3 was made. The fraction of the amount of NH3
to be desorbed at 300 to 800° C. based on the total amount of
NH3 to be desorbed is shown in Table 1. Metals were carried on the
carrier by the Pore-filling method so that the contents of the metals
were as shown in Table 1, and sulfurized to obtain a first catalyst.

[0075] In Examples other than Example 1, a carrier was prepared by
adjusting the concentration of Solution A, Solution B, and Solution C so
that the composition of the carrier shown in Table 1 was satisfied, and
metals were carried on the obtained carrier by the Pore-filling method so
that the contents of the metals were as shown in Table 1, and sulfurized
to obtain a first catalyst.

[0076] Next, the catalyst shown in Table 1 above and the slack wax having
properties shown in Table 2 below were contacted with each other under
the condition shown in Table 3 to obtain a produced oil having properties
shown in Table 3 (first produced oil). In the table, the cracking rate
indicates a value determined from a yield of the component having not
more than 19 carbon atoms in the produced oil determined by a gas
chromatography analysis, and the isomerization rate indicates a value
determined from the proportion of the isomer in the component having not
less than 20 carbon atoms determined by a gas chromatography analysis.
Moreover, the sulfur content indicates a value measured according to JIS
K2541 "Crude Oil and Petroleum Products-Sulfur Content Test Method," and
the nitrogen content indicates a value measured according to JIS K2609
"Crude Oil and Petroleum Product-Nitrogen Content Test Method."

[0077] Next, each of the first produced oils obtained in Examples 1 to and
Comparative Examples 1 to 8 was subjected to the hydrogenation treatment
(hydrogenation dewaxing step) on the condition shown in Table 4 below to
obtain a second produced oil. In the table, the content of the normal
paraffins having not less than 20 carbon atoms indicates a value
determined by a gas chromatography analysis. In the first produced oil
obtained in Comparative Example 9, a methyl ethyl ketone/toluene mixed
solvent (mixing proportion of 50 volume %/50 volume %) was added by the
amount 3.5 times the amount of the first produced oil, and solvent
dewaxing by filtration at -32° C. was performed; the produced oil
after the solvent dewaxing was used as the second produced oil.

[0078] Further, the second produced oil was subjected to the hydrogenation
treatment (hydrorefining step) in the presence of the catalyst, in which
the active metal was platinum and the carrier was alumina, on the
condition of the reaction temperature of 220° C., the LHSV of 2
h-1, the hydrogen partial pressure of 5 MPa, and the hydrogen/oil
ratio of 3000 scf/b to obtain a third produced oil. The obtained third
produced oil was fractionated by distillation under reduced pressure to
obtain a 70 Pale base oil that is a fraction at 340 to 410° C. in
terms of normal pressure, an SAE 10 base oil that is a fraction at 390 to
470° C. in terms of normal pressure, an SAE 20 base oil that is a
fraction at 450 to 520° C. in terms of normal pressure, and an SAE
30 base oil that is a fraction at 510 to 550° C. in terms of
normal pressure. The yields and properties of the obtained base oils were
as shown in Table 5. The kinematic viscosity (100° C.) and the
viscosity index (VI) were measured according to JIS K2283 "Crude Oil and
Petroleum Products-Kinematic Viscosity Test Method and Viscosity Index
Calculation Method," and the pour point was measured according to JIS
K2269 "Pour Point of Crude Oil and Petroleum Products and Cloud Point of
Petroleum Products Test Method." In each of Examples, a high quality
lubricant base oil could be obtained with a high yield.